Related Experiment Video
Updated: Oct 16, 2025
Gene Regulation and Targeted Therapy in Gastric Cancer Peritoneal Metastasis: Radiological Findings from Dual Energy CT and PET/CT
Published on: January 22, 2018
Histological regression of gastrointestinal peritoneal metastases after systemic chemotherapy
Laura Toussaint1, Hugo Teixeira Farinha1, Jean-Luc Barras2
1Department of Visceral Surgery, Lausanne University Hospital (CHUV), University of Lausanne (UNIL), Lausanne, Switzerland.
Objectives:
Peritoneal metastases (PM) are relatively resistant to systemic chemotherapy, and data on histological response to therapy is rare. The aim of this study was to quantify the treatment response of PM after systemic chemotherapy.
Methods:
Retrospective monocentric cohort study of 47 consecutive patients with PM from gastrointestinal origin undergoing surgery (cytoreduction: CRS + Hyperthermic IntraPEritoneal Chemotherapy [HIPEC] or Pressurized IntraPeritoneal Aerosol Chemotherapy [PIPAC]) after prior systemic chemotherapy from 1.2015 to 3.2019. Tumor response was assessed using the 4-scale Peritoneal Regression Grading System (PRGS) (4: vital tumor to 1: complete response).
Results:
Patients had a median of 2 (range: 1-7) lines and 10 (3-39) cycles of prior systemic chemotherapy. A median of four biopsies (range: 3-8) was taken with a total of 196 analyzed specimens. Twenty-four biopsies (12%) showed no histological regression (PRGS4), while PRGS 3, two and one were diagnosed in 37 (19%), 39 (20%), and 69 (49%) specimens, respectively. A significant heterogeneity was found between peritoneal biopsies in 51% patients. PRGS correlated strongly with peritoneal spread (PCI, p<0.0001), and was improved in patients with more than nine cycles of systemic chemotherapy (p=0.04). Median survival was higher in patients with PRGS < 1.8 (Quartiles one and 2) than higher (Q3 and Q4), but the difference did not reach significance in this small cohort.
Conclusions:
PRGS is an objective too to describe histological response of PM of GI origin after systemic chemotherapy. This response differs significantly between patients, allowing to distinguish between chemosensitive and chemoresistant tumors.
Insights
Peritoneal metastases (PM) response to chemotherapy varies. The Peritoneal Regression Grading System (PRGS) quantifies histological changes, identifying chemosensitive versus chemoresistant tumors in gastrointestinal cancers.
Area of Science:
- Oncology
- Gastroenterology
- Surgical Oncology
Background:
- Peritoneal metastases (PM) from gastrointestinal cancers exhibit resistance to systemic chemotherapy.
- Histological response data for PM after systemic therapy is limited.
- Quantifying treatment response is crucial for understanding therapeutic efficacy.
Purpose of the Study:
- To quantify the histological treatment response of peritoneal metastases (PM) after systemic chemotherapy.
- To evaluate the utility of the Peritoneal Regression Grading System (PRGS) in assessing PM response.
- To identify factors influencing treatment response in PM.
Main Methods:
- Retrospective monocentric study of 47 patients with gastrointestinal PM.
- Patients received cytoreductive surgery (CRS) with HIPEC or PIPAC post-systemic chemotherapy.
- Tumor response assessed using the 4-scale Peritoneal Regression Grading System (PRGS).
Main Results:
- A median of 10 cycles of systemic chemotherapy was administered prior to surgery.
- PRGS scores indicated varying degrees of regression, with 49% showing complete response (PRGS 1).
- Significant heterogeneity in regression was observed in 51% of patients.
- Higher PRGS scores correlated with lower peritoneal cancer index (PCI).
- More than nine cycles of chemotherapy improved PRGS scores (p=0.04).
Conclusions:
- The Peritoneal Regression Grading System (PRGS) provides an objective measure of histological response in PM of GI origin.
- Significant inter-patient variability in response allows differentiation between chemosensitive and chemoresistant tumors.
- PRGS aids in evaluating treatment efficacy and guiding therapeutic strategies for PM.
